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1 | /** @file\r | |
2 | PEI Dispatcher Dependency Evaluator\r | |
3 | \r | |
4 | This routine evaluates a dependency expression (DEPENDENCY_EXPRESSION) to determine\r | |
5 | if a driver can be scheduled for execution. The criteria for\r | |
6 | schedulability is that the dependency expression is satisfied.\r | |
7 | \r | |
8 | Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>\r | |
9 | This program and the accompanying materials \r | |
10 | are licensed and made available under the terms and conditions of the BSD License \r | |
11 | which accompanies this distribution. The full text of the license may be found at \r | |
12 | http://opensource.org/licenses/bsd-license.php \r | |
13 | \r | |
14 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r | |
15 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r | |
16 | \r | |
17 | **/\r | |
18 | \r | |
19 | #include "PeiMain.h"\r | |
20 | #include "Dependency.h"\r | |
21 | \r | |
22 | /**\r | |
23 | \r | |
24 | This routine determines if a PPI has been installed.\r | |
25 | The truth value of a GUID is determined by if the PPI has\r | |
26 | been published and can be queried from the PPI database.\r | |
27 | \r | |
28 | \r | |
29 | @param PeiServices An indirect pointer to the EFI_PEI_SERVICES table published by the PEI Foundation\r | |
30 | @param Stack Reference to EVAL_STACK_ENTRY that contains PPI GUID to check\r | |
31 | \r | |
32 | @retval TRUE if the PPI is already installed.\r | |
33 | @retval FALSE if the PPI has yet to be installed.\r | |
34 | \r | |
35 | **/\r | |
36 | BOOLEAN\r | |
37 | IsPpiInstalled (\r | |
38 | IN EFI_PEI_SERVICES **PeiServices,\r | |
39 | IN EVAL_STACK_ENTRY *Stack\r | |
40 | )\r | |
41 | {\r | |
42 | VOID *PeiInstance;\r | |
43 | EFI_STATUS Status;\r | |
44 | EFI_GUID PpiGuid;\r | |
45 | \r | |
46 | //\r | |
47 | // If there is no GUID to evaluate, just return current result on stack.\r | |
48 | //\r | |
49 | if (Stack->Operator == NULL) {\r | |
50 | return Stack->Result;\r | |
51 | }\r | |
52 | \r | |
53 | //\r | |
54 | // Copy the Guid into a locale variable so that there are no\r | |
55 | // possibilities of alignment faults for cross-compilation \r | |
56 | // environments such as Intel?Itanium(TM).\r | |
57 | //\r | |
58 | CopyMem(&PpiGuid, Stack->Operator, sizeof(EFI_GUID));\r | |
59 | \r | |
60 | //\r | |
61 | // Check if the PPI is installed.\r | |
62 | //\r | |
63 | Status = PeiServicesLocatePpi(\r | |
64 | &PpiGuid, // GUID\r | |
65 | 0, // INSTANCE\r | |
66 | NULL, // EFI_PEI_PPI_DESCRIPTOR\r | |
67 | &PeiInstance // PPI\r | |
68 | );\r | |
69 | \r | |
70 | if (EFI_ERROR(Status)) {\r | |
71 | return FALSE;\r | |
72 | }\r | |
73 | \r | |
74 | return TRUE;\r | |
75 | }\r | |
76 | \r | |
77 | /**\r | |
78 | \r | |
79 | This is the POSTFIX version of the dependency evaluator. When a\r | |
80 | PUSH [PPI GUID] is encountered, a pointer to the GUID is stored on\r | |
81 | the evaluation stack. When that entry is poped from the evaluation\r | |
82 | stack, the PPI is checked if it is installed. This method allows\r | |
83 | some time savings as not all PPIs must be checked for certain\r | |
84 | operation types (AND, OR).\r | |
85 | \r | |
86 | \r | |
87 | @param PeiServices An indirect pointer to the EFI_PEI_SERVICES table published by the PEI Foundation\r | |
88 | @param DependencyExpression Pointer to a dependency expression. The Grammar adheres to\r | |
89 | the BNF described above and is stored in postfix notation.\r | |
90 | \r | |
91 | @retval TRUE if it is a well-formed Grammar\r | |
92 | @retval FALSE if the dependency expression overflows the evaluation stack\r | |
93 | if the dependency expression underflows the evaluation stack\r | |
94 | if the dependency expression is not a well-formed Grammar.\r | |
95 | \r | |
96 | **/\r | |
97 | BOOLEAN\r | |
98 | PeimDispatchReadiness (\r | |
99 | IN EFI_PEI_SERVICES **PeiServices,\r | |
100 | IN VOID *DependencyExpression\r | |
101 | )\r | |
102 | {\r | |
103 | DEPENDENCY_EXPRESSION_OPERAND *Iterator;\r | |
104 | EVAL_STACK_ENTRY *StackPtr;\r | |
105 | EVAL_STACK_ENTRY EvalStack[MAX_GRAMMAR_SIZE];\r | |
106 | \r | |
107 | Iterator = DependencyExpression;\r | |
108 | \r | |
109 | StackPtr = EvalStack;\r | |
110 | \r | |
111 | while (TRUE) {\r | |
112 | \r | |
113 | switch (*(Iterator++)) {\r | |
114 | \r | |
115 | //\r | |
116 | // For performance reason we put the frequently used items in front of \r | |
117 | // the rarely used items\r | |
118 | //\r | |
119 | \r | |
120 | case (EFI_DEP_PUSH):\r | |
121 | //\r | |
122 | // Check to make sure the dependency grammar doesn't overflow the\r | |
123 | // EvalStack on the push\r | |
124 | //\r | |
125 | if (StackPtr > &EvalStack[MAX_GRAMMAR_SIZE-1]) {\r | |
126 | DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));\r | |
127 | return FALSE;\r | |
128 | }\r | |
129 | \r | |
130 | //\r | |
131 | // Push the pointer to the PUSH opcode operator (pointer to PPI GUID)\r | |
132 | // We will evaluate if the PPI is insalled on the POP operation.\r | |
133 | //\r | |
134 | StackPtr->Operator = (VOID *) Iterator;\r | |
135 | Iterator = Iterator + sizeof (EFI_GUID);\r | |
136 | DEBUG ((DEBUG_DISPATCH, " PUSH GUID(%g) = %a\n", StackPtr->Operator, IsPpiInstalled (PeiServices, StackPtr) ? "TRUE" : "FALSE"));\r | |
137 | StackPtr++;\r | |
138 | break;\r | |
139 | \r | |
140 | case (EFI_DEP_AND): \r | |
141 | case (EFI_DEP_OR): \r | |
142 | if (*(Iterator - 1) == EFI_DEP_AND) {\r | |
143 | DEBUG ((DEBUG_DISPATCH, " AND\n"));\r | |
144 | } else {\r | |
145 | DEBUG ((DEBUG_DISPATCH, " OR\n"));\r | |
146 | }\r | |
147 | //\r | |
148 | // Check to make sure the dependency grammar doesn't underflow the\r | |
149 | // EvalStack on the two POPs for the AND operation. Don't need to\r | |
150 | // check for the overflow on PUSHing the result since we already\r | |
151 | // did two POPs.\r | |
152 | //\r | |
153 | if (StackPtr < &EvalStack[2]) {\r | |
154 | DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));\r | |
155 | return FALSE;\r | |
156 | }\r | |
157 | \r | |
158 | //\r | |
159 | // Evaluate the first POPed operator only. If the operand is\r | |
160 | // EFI_DEP_AND and the POPed operator evaluates to FALSE, or the\r | |
161 | // operand is EFI_DEP_OR and the POPed operator evaluates to TRUE,\r | |
162 | // we don't need to check the second operator, and the result will be\r | |
163 | // evaluation of the POPed operator. Otherwise, don't POP the second\r | |
164 | // operator since it will now evaluate to the final result on the\r | |
165 | // next operand that causes a POP.\r | |
166 | // \r | |
167 | StackPtr--;\r | |
168 | //\r | |
169 | // Iterator has increased by 1 after we retrieve the operand, so here we \r | |
170 | // should get the value pointed by (Iterator - 1), in order to obtain the \r | |
171 | // same operand.\r | |
172 | //\r | |
173 | if (*(Iterator - 1) == EFI_DEP_AND) {\r | |
174 | if (!(IsPpiInstalled (PeiServices, StackPtr))) {\r | |
175 | (StackPtr-1)->Result = FALSE;\r | |
176 | (StackPtr-1)->Operator = NULL;\r | |
177 | }\r | |
178 | } else {\r | |
179 | if (IsPpiInstalled (PeiServices, StackPtr)) {\r | |
180 | (StackPtr-1)->Result = TRUE;\r | |
181 | (StackPtr-1)->Operator = NULL;\r | |
182 | }\r | |
183 | }\r | |
184 | break;\r | |
185 | \r | |
186 | case (EFI_DEP_END):\r | |
187 | DEBUG ((DEBUG_DISPATCH, " END\n"));\r | |
188 | StackPtr--;\r | |
189 | //\r | |
190 | // Check to make sure EvalStack is balanced. If not, then there is\r | |
191 | // an error in the dependency grammar, so return EFI_INVALID_PARAMETER.\r | |
192 | //\r | |
193 | if (StackPtr != &EvalStack[0]) {\r | |
194 | DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));\r | |
195 | return FALSE;\r | |
196 | }\r | |
197 | DEBUG ((DEBUG_DISPATCH, " RESULT = %a\n", IsPpiInstalled (PeiServices, StackPtr) ? "TRUE" : "FALSE"));\r | |
198 | return IsPpiInstalled (PeiServices, StackPtr);\r | |
199 | \r | |
200 | case (EFI_DEP_NOT): \r | |
201 | DEBUG ((DEBUG_DISPATCH, " NOT\n"));\r | |
202 | //\r | |
203 | // Check to make sure the dependency grammar doesn't underflow the\r | |
204 | // EvalStack on the POP for the NOT operation. Don't need to\r | |
205 | // check for the overflow on PUSHing the result since we already\r | |
206 | // did a POP.\r | |
207 | //\r | |
208 | if (StackPtr < &EvalStack[1]) {\r | |
209 | DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));\r | |
210 | return FALSE;\r | |
211 | }\r | |
212 | (StackPtr-1)->Result = (BOOLEAN) !IsPpiInstalled (PeiServices, (StackPtr-1));\r | |
213 | (StackPtr-1)->Operator = NULL;\r | |
214 | break;\r | |
215 | \r | |
216 | case (EFI_DEP_TRUE):\r | |
217 | case (EFI_DEP_FALSE):\r | |
218 | if (*(Iterator - 1) == EFI_DEP_TRUE) {\r | |
219 | DEBUG ((DEBUG_DISPATCH, " TRUE\n"));\r | |
220 | } else {\r | |
221 | DEBUG ((DEBUG_DISPATCH, " FALSE\n"));\r | |
222 | }\r | |
223 | //\r | |
224 | // Check to make sure the dependency grammar doesn't overflow the\r | |
225 | // EvalStack on the push\r | |
226 | //\r | |
227 | if (StackPtr > &EvalStack[MAX_GRAMMAR_SIZE-1]) {\r | |
228 | DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));\r | |
229 | return FALSE;\r | |
230 | }\r | |
231 | //\r | |
232 | // Iterator has increased by 1 after we retrieve the operand, so here we \r | |
233 | // should get the value pointed by (Iterator - 1), in order to obtain the \r | |
234 | // same operand.\r | |
235 | //\r | |
236 | if (*(Iterator - 1) == EFI_DEP_TRUE) {\r | |
237 | StackPtr->Result = TRUE;\r | |
238 | } else {\r | |
239 | StackPtr->Result = FALSE;\r | |
240 | }\r | |
241 | StackPtr->Operator = NULL;\r | |
242 | StackPtr++;\r | |
243 | break;\r | |
244 | \r | |
245 | default:\r | |
246 | DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Invalid opcode)\n"));\r | |
247 | //\r | |
248 | // The grammar should never arrive here\r | |
249 | //\r | |
250 | return FALSE;\r | |
251 | }\r | |
252 | }\r | |
253 | }\r |